Low-level Microwave Radiation Research Articles

Psychoactive-drug response is affected by acute low-level microwave irradiation.

The effects of various psychoactive drugs were studied in rats exposed for 45 min in a circularly polarized, pulsed microwave field (2450 MHz; SAR 0.6 W/kg; 2-microseconds pulses, 500 pps). Apomorphine-induced hypothermia and stereotypy were enhanced by irradiation. Amphetamine-induced hyperthermia was attenuated while stereotypy was unaffected. Morphine-induced catalepsy and lethality were enhanced by irradiation at certain dosages of the drug. Since these drugs have different modes of action on central neural mechanisms and the effects of microwaves depend on the particular drug studied, these results show the complex nature of the effect of microwave irradiation on brain functions.

Effect of low-level microwave irradiation on the duodenal electrical activity of the unanesthetized rat.

The effects of low-level microwave irradiation (5 and 7.5 mW/cm2 at 2.45 GHz) on duodenal electrical activity (slow waves and action potentials) were studied in the unanesthetized rat by way of chronically implanted electrodes. Exposure to microwaves occurred in a cavity for 1 to 4 hours. The specific absorption rates (SAR) were measured at 5.35, 6.05, and 7.04 mW/g, respectively, under 5, 7.5, and 10 mW/cm2 of incident radiation. The results, obtained on seven rats, showed that microwaves usually produce an accelerating effect on the slow waves, and a specific inhibitory effect on action potentials. Those effects appear to be directly dependent on the SAR.

Combined Effects of Anticholinesterase Drugs and Low-Level Microwave Radiation

Rats administered an anticholinesterase drug (phospholine iodide) and exposed 10 min later to a pulsed microwave irradiation with an average power density of 10 mW/ cm2 for 10 min showed a statistically significant decrease in body temperature when compared to various control groups. The enhancement of hypothermia in the presence of low-level microwave irradiation was also observed when rats were injected with another powerful inhibitor of acetylcholinesterase, paraoxon, and with 2-pyridine aldoxime methyl methanesulfonate, an antidote against anticholinesterase poisoning. The effect from the combination of microwave and anticholinesterase drugs may potentially be used as a tool to study effects of low-power density microwave fields on biological systems.

The effect of environmental temperature and average dose rate of microwave radiation on the oxygen-consumption rate of mice.

The oxygen consumption rate of CF1 male mice was determined before, during, and after sham- and microwave-irradiation at environmental temperatures of 20 degrees C, 24 degrees C, 30 degrees C, and 35 degrees C, relative humidity of 55%, and air flow rate of 78 ml/min. Five forward power levels ranging from 0.09 to 3.3 W, which resulted in corresponding average dose rates ranging from 1.2 to 45.1 mW/g were used. The values of the oxygen consumption rate were converted to those of the specific metabolic rate (SMR). The result indicates that with high levels of microwave dosing (greater than 10 mW/g) the specific metabolic rate of mice decreased in some cases, in the environmental temperatures of 20 degrees C and 24 degrees C. However, the decreased SMR values were not lower than the SMR values of the sham-irradiated group in 30 degrees C. In the case of 35 degrees C, the high level dosing with microwave radiation caused increases in the SMR value over the sham value. A possible trend towards increased SMR value during and after irradiationwith low level (1.6 mW/g) microwave radiation in the environmental temperatures of 24 degrees C and 30 degrees C suggests further experiments with low level microwave radiation to determine possible effects of low level microwave radiation in stimulating increases in specific metabolic rate.

Effects of Low Level Microwave Radiation on the Digestive Transit of the Rat

The effects of low level microwave radiation (3-4 mW/cm2--2450 MHz) during 4 and 8 h on the WISTAR Rat digestive transit has been studied. The results showed no effect after 4 h radiation and an acceleration of the digestive transit after 8 h of radiation (p less than .001). The acceleration of the digestive transit was still observed after 24 h (p less than .001). 60-90 s after radiation time the rectal temperature of radiated animals did not differ from the controls.

Low-intensity microwave radiation and the virulence of Agrobacterium tumefaciens strain B6.

When virulent cells of Agrobacterium tumefaciens strain B6 were exposed to low-level microwave radiation at a frequency of 10,000 MHz and an intensity of 0.58 mW/cm2 for 30 to 120 min, a 30 to 60% decrease in their ability to produce tumors on potato and turnip disks was observed. This microwave exposure did not affect the viability of these bacteria or their ability to attach to a tumor-binding site nor did it induce thermal shock. This loss of virulence was reversible within 12 h.

Effects of low-level microwave radiation on germination and growth rate in corn seeds

Experiments were conducted to investigate the effects of microwave radiation on germination and growth rate in corn seeds. Specimens were irradiated in an anechoic chamber, for 22 to 24 h, at CW power density levels from 10 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> to 30 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The radiation frequency was 9 GHz. Marked inhibition of seed germination was observed in radiated specimens, probably as a result of water loss.

Biological effects of microwave radiation.

The possibility of exposure of large segments of the population to complex, multifrequency microwave radiation in the environment is now a reality. It is necessary, therefore, to determine the safe level of exposure for the general population so as to prevent any occurrence of harmful effects without unduly restricting the beneficial uses of microwaves. The biological effects generated by exposure to microwave radiation are usually designated as thermal or non-thermal (specific) in nature. Thermal effects are those interactions which are caused by the heating of the biological specimen and can be duplicated using conventional heating techniques. Nonthermal or specific effects are due to the direct interaction of the electromagnetic field of the incoming microwave radiation and the biological specimen. The two organs of the body which are particularly sensitive to elevation in temperature are the testicles and the eyes. These organs, therefore, are the most sensitive to exposure to microwave radiation. Research on dogs, rabbits, and rats has shown that at 10 mW/cm, (power density in milliwatts per square centimeter) pathological damage to the testes include a degeneration of the epithelium lining of the seminiferous tubules, and a sharp reduction in the number of maturing spermatocytes. The reduction in testicular function due to the heating effect at 10 mW/cm2 appears to be temporary and reversible. Cataracts have been produced in the eyes of experimental animals. Several investigators have used the eyes of rabbits to establish threshold for cataract formation. For CW radiation, the threshold in rabbits for long-term ex-posure, was measured to be approximately 100 mW/cm2. Several cases of eye cataracts in man due to microwave exposure have been reported at power densities of the same order of magnitude. More research is needed before threshold values for cataract formation in humans can be specified with certainty. Nonthermal or specific effects are more difficult to detect than the thermal effects. This difficulty is due to the nature of the response of the biological specimen and the lack of explanation of the mechanism causing the effect. The most often reported effects of low level microwave radiation are neurological in nature. Effects on animals include changes in EEG patterns, changes in the conditioned reflexes, alterations in sensitivity to light, sound, and olfactory stimuli, alterations in the biocurrents of the cerebral cortex, and changes in behavior. Many subjective symptoms in humans working around microwave equipment have been reported by investigators from the U.S.S.R. and Eastern European researchers. Genetic effects have been reported by some investigators. Exposure of chick embryos to microwave radiation induced abnormal development while conventional heating to the same temperature did not cause abnormalities. In general, the abnormalities appeared to be caused by the inhibition of growth and cell differentiation. Abnormal development of the “mealworm” beetle pupae has also been detected when exposed to microwave radiation. This study also indicates that the abnormalities were not due to thermal effects but due to the inhibition of cell differentiation caused by a direct interaction with the electromagnetic field.

Absence of Heart-Rate Effects in Rabbits During Low-Level Microwave Irradiation

Soviet studies have reported that low-level microwave irradiation alters the heart rate of humans and animals. In a replication of one such study, 16 rabbits were exposed to dorsal irradiation n of the head by 2.4-GHz CW. microwaves at a power density of 10 mW /cm/sup 2/ for 20 min. The rest of the animal's body was shielded by absorbent material. There was no significant difference between the heart rate during or after irradiation and the heart rate of the same animals during a control condition in which they were not irradiated. Analysis of the variability in heart rate observed in this experiment suggested that the heart-rate effects reported in the original Soviet study might have been chance variations. In a second experiment, heart rate, respiration rate, and body temperature were recorded simultaneously while each of two rabbits was irradiated as before, on the dorsal aspect of the head only, at various power densities from 0 to 100 mW/cm/sup2/, in steps of 20 mW/cm/sup 2/. Respiration rate increased during irradiation at 40 mW/cm/sup 2/, body temperature rose at 80 mW/ cm/sup 2/, and ultimately the heart rate also increased, but only at 100 mW/cm/sup 2/.